• -.. I I
• • 0 REPUBLIC OF BOTSWANA
• • THE '10CHUOI GROUNOIJATER EXPLORATION PROJECT
U (1982 - 1983) Final Report
I I O. K. 8UCKLEY
I GS/OKB/4/83 ~OVEI1BER 1983.
J
• • Department of Geological Survey
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" PRINTED BY THE COVERNMENT PRINTER. GABORONE
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Ill/ r10CIIIIOI CfWllNDHAHR [XPl OHI\IItl~ PiHJJl L ,
I ~ I RUllllI I [(J~
II-U ARlA
rllfu::ltp
\'(''1'" alioll
I XIS! '''G iJ:\lru 'iUrPlY
Inlroduclioll
Current abslrort lon
Aqul r er water 1t'\lrJs
H:Jtrr quality
rulur~ ..... alrr drmand
I'HI \, WlJS CHUUr-..m/A 1 (R I XrUIHrd ION
JIJJ4-IQ',7 '!'lIbl If' UIII k·; [)l'p:lrlmf'llt)
J'I)6-1lj~ 7 (l.;C'ulotJlf'al Su r vpy)
1974-1977 (DepartmenL of ~1<1ler Arf ans)
GEOLOGY
6. IHl STUDY ARIA
7 . INVlSIIGA111lN TICHNTQU[S
7.1 Hev i e\il or cxisUng dala
7 . 1 . J 1101 ('hole l'('cunJs
7 . 1. 2 I,( l nllny ypophyslu11 do l o
7. 1. 3 I xl',lint) purnplllq Lesl data
7 . 2 InLcrp rclalJOn or !;o l cllllc imagery
7 . 3 Inlerpretatiun of air photog r aphy
7 .4 Surface geophysIcal s t udies
7.u.1 lIagnctomeLf>r lraverses
7 . U . Z l1prlricai ro;>si5t.lVlty measuremenlq
7 . '.; ! "plul"ation dri.lling l'll1d lesllny
8 . IlIl RlSUI IS or l"~lSllGAT1l1\
0 . 1 11l11plablt' of ;lclJVltlCS
0.2 Drill i ng
C. 2 . 1 t Ith,} } rHJY
0 . 2.2 l'l'lIptraLlon ra Lcs
B. 2 . J \"/;ILrt" ~;trikc~
0.2.4 UnLer J{'vel"
8.2 . 5 Ilorchole top clev::~Lion survey
e. ) Gpophysi.cal boreho l e loggwg
8 . 4 Pumping Les ls
8 . 4 .1 ConsLant rate tests
8.4 . Z Step uravdo~n lesls
8 . 4.3 rlolJlmelcr rncasurcmpnls
O. 4 . U Summary of pumping lesls r esulls and anll t ys l S
O. S I he aqui fers
0 . 5 . 1 lhe granile - gneiss aquife r
8 . 5 . 2 lhe HLllprbcry aquifer
8 . ~I. J The' aqu.l fe r syslem
B.S .4 ~Iale r le ve l f1ucluatiolls
0.5.'.; GroumJIIILltr'r rJow
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• ~
• • • • I I m
• • m
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• • -
• • ...
0 . 5 . 6
8 .6
\/nler quality
lnLIc<d rev ipw or boceho!c siting
lC'rhfliques
Q (·IAII H IHSUUHlTS
9 . 1 IlvdruJuqlC'nl processe!1
9.2 A\lIiJl('rbal<lllce
9 . 3 Gnluf}th:mlrf t f'chargc
9 . 4 AquIfer sloroyr'
rl,5 necnmmf'llrled puwp lily rates
10. I'OlLUIIO"J
W.l Illlroducllon
10.2 Prf'vious pollution 9tud~es
10.2 . 1 Hutloll , LCWlS ~Hld SkinnPf , Janunry 1976
10.2.2 Slit ClJ/SlDA 1977-78
10.2 . 3 roster, rnrr alld lcvis, June 1978
10.2.4 lhomson, June 1978
10 . 3 Present sltuation
10.4 Summary and recommendalions
J1. SUIU1AHY A"J11 COr-;ClUSIONS
12 . fHr[HENn~;
rigure
r .lgure 2
r iyu l c J
I lqU I'P U.
r1(Jure ,
f jrJurc B
r igure 9
t 151 ur r I LUIIf ~,
location mOJ1
"on lhl y mealls
Pcrcenl£1gC' rninfnll var inli un . l1uchudl
I 9u.U-l 'JEl2
non l h I y mean pumpE'd ilia If' r , f'nt'hud 1
Hyul'ufJco logical scc l.l on lI11lHHjh !·'<.l~llllfl
burcholcs (l-W)
Ar rom;ltjlll' l It' m;1p
Yleld-drallldml/n characlcf.lsl lc" , 110chudl
uo r choles
rorcr<l'Jl d r<l lllc!own, borehole 850 And 2704
r .lqurc la lineament interpretalion, satellile sccne
22369-97261
f 19ure 11 Lineaments close to "ochudi village
f lqure 12 ~'agnelomeler profiles MT 12, 18, 19, 15
r lyure 13 t-laynelomeler profiles ~1T 15, 13, 14, 17
r 19ure J4 f1<lynelomelcr profiles HT 8 , 21, 6, 22
rlgure 15 Magnelomcter profiles m 1,47,43, 11, 42, 44
rigure 16 Hagnelomeler profiles MT 4 , 54, 24
r 19ure 17 Hagnclomcler profiles MT 56 , 55 , 37
f.lgurc 10 Resistivity sounding curves
r.l yure 19 He~HSl.lvily lraverses
" I ltJure 20 Rcs .l sllvily sections , borehole 4258 area
f lyurc 21 Hesisl.lvity map, borehole 4250 area
figure 22 Geoloqlcol secl ion, borehole 4258 area
f.lgure 23 Penetration rate logs
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r I (Jure 24
lqure 25
IfjlllP 7.6
II'-Jurc 27
r I qll r(' ,0
I 'Jure 29
If/ure ;0
r iqur,.. 31
IlfJlJfC J2
I i, j' Jfr ~'J
HJUfe J4
If Jure 3~
• Hydrogeoloyical secl l on NW-SE
IlydruIJPologlcal scc Lion ~W-M
flmf"-dr<lvllown meOSUfCml'nt'1, DHA \("11 d<ltn
I imf'-,Jrawrjollln , burL'l10 11' 6266
r' mp -druwdOlUn borf'holf' 42~n , I~~HI~, 4JfJ6
d-druvdowrl, bOft'hole 1I2C,fJ , 4245 , :'.54<)
fl owme t e r fTlI'asur('mrnls uo["cholp 424J , 454:'
Waler lE' vc I Iluctu<1L ions
irilinf'ar dlagr~m
10 ciA)' cOlnfall and potl'llll:lL ""\' ~I!'flr;d ion ,
l10chudt bOfPhales 1902-1'183
Ni t falc le\lc1s in f1ocl'ludi borcholPG 1900- 1YIl'
Chloride lc\.cl!:i in flochudi borphoipr, JI.IB(1-I'ln_~
•
iutdp
iuht!' 2
Inblp >
lilllll> 4
I able 5
I ab le 6
!able 7
lahle 8
1 able 9
fable 10
Table 11
lable 12
Table IJ
I~ble 14
lable 15
l;:Jblc 16
lable 17
labJe 18
Summary or valer pumpeu, Jlochuui 1978-82
rlf'<Ul dally ahstraclion 1970-82
Ileon pumping raLcs , f10chudi bon'hole::;
lsllmolcd domcslic lIIaler rcqu.lfcmcnt
I?Bl-1991
Summary or drilllnq records. st\f'el 2426A
Summary or dr,lllul(j records, l1uchudl vi Ila~w
urea
r,umrn~r)' of existIng pumping lest del:"}
DrawrlnVIl equations
Tlonsmisslvilles and SpCClr.lC I..'JPocit I('!j
Ilf'slsli" lty :;;oundiny dala summary
Ilmetablc or maln activitIes
Summary or constant rale pumpl.llY lest re sult'>
Summary or step drawdevll If'sl resulls
RpCOfllmf'ndcd pump 1ng rah~s and expected drAllldovn~
Chemical analyses or waler from b9fchoies dr.1 I Ird
lhcmJcal analyses of lIIater from cX.1slinq borrhulc!~
Evaporation esljmal~s , Gaborone dala
10- day mC<Jn Penman potential evapotransplrallOl1
and eXCC!lS rainfall events , r--1ochudl 1970-82
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• • • • L I ~i1 ur MAr~; • • • Al r pho to lrltcrprclaliol1
!lap '1 Ion!! lUll of maYl1clornelf"r traverses and
11 c I er I r lea 1 sound i.ngs
• l1<lp J Bnrf'llUll' lo('atiul1s
l'unlC'n13 of Appendil( • • I . IllI r ('III,I(> detaI l "
• 2. \hJ!"r If'tf'l m,,;-J'-.u r rmrn l !"i , rXlsl lnq borellulf'!:;
1 .. ;1 nl tlfll'pholf' top e l£'vnt Jilll">
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I. [\IHOOIJCllUN
In Jnnuary, 1982 flochudl village \IIas idenlir.lcd by the Oeparlmenl
u f U;t l. I A rr"lr ~; ;t', <I major vilJaqc In urqenl 1I('('d uf an cxlpnsjon In
lls U<.dPf supply. Al t hat limr consullanls lIIere bC'tng in'vilptl to
t;ubrllil Plupo!l;lls f or the South East Oot!'>lIIana Regional WOalf'f study. LI
llUJI ;Pld JUf'ld i fy suurces nf I,ml"f for lhr major v Illog('o:; alld popula
l Ion cUll re ~ throughout the castern P,!I't 'of the ruuflt ry. III \;11"V of
the sllurl • .Hl" of lIIalf'1" in Huchudi and cOlllamlnatlDIl of some of 11 11' h(I'''-
hair"; ':I IPlll)'lllll thl' VI llnge it was decided lo carry aul yruuwJw;)trr
(''I(plUI;l tlon fur the v dlagc Ifl ill.h;:lIIC'C of the flndlflfJs "r \1,,· rl"llon;11
!lludy. [he G('(duq ical Survpy \l/a5 asked I n ("arry flul lI,,' p'\l'inr;:lI lW,
t I ua'i d("1 idC'd lo C';Jr r} out an OXI' JUI allull l 'n'JI'I L Ul,lc!l il .ll1 lf",j fIn!
Ufll\" lu lOCillf' lhe' much Ilpcded gfoulld\ll:1ll'r but al-;o 10 \ilk£' Ihp OIPO(
l Ufli l y lu 1j<.l!1I a beller undC'rslarH.hl.tj of Ihp IJH~>('lI1crrl rude.' WIU! rr-f!') , uhi("'h I'ould be of vaiup lo rulure studies in othl'r parl'; of the l',,,,,dIY·
UUI k l'flr'lI111'II,"rd 011 lhr project .ln I1arch, )902.
2 . TilE AHLA
I1ndl\ltla 1<; tlrp c':lpillr\ of the BakYi:lLla Lr.loC" and adminislraLl\;c
760(1. km'). 1 t 15 loC'alrd C'in'w to tile
, ,11 }d! I~I\I'J Uhl'i'" I1 fnll ulliS Ih,' IIIulI1ll1rnl e<;rnqu"I'I.1 ur \/;ltt>I-brrq
"" k·" ; UIj1P -'If! km 1IIIIIh 01 t;~lhllrullc (I l1JlIlP 1).
,
REPUBLIC OF nOTSW ANA
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2426A --+--
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Figure 1 Location map
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file v l ll;HIf' ll~;l'lf h;l!..i dcveloprd un Ih(' hlljh [jround por-tt. o f 1111'
I l ll'l 011 t la' f"a'aqJRlPnL . I he t1.lstorJC'Di (,(,Illrl' of 1111' \ I J 1119(' J<"; '11
f'hulhiHJI~ullo lid!, lllc vl ll aye has de ve loped cc',,!w<lnl'; Nt~;hlUOf, •• Vf',> I _
vald~; Ib<;rfuld ;IIH.J ~iUuth across thp r.lvcr (Uo~j('J;I) . Ihp :II'r;1 sOl/ lh u f
tlH' fJ\.;I'1 ".:1 V;Jr,t f lat pL1 1I 1 or 0111('11'111 'JI';uulf'-lIfll'l'';S 1'1)( k;1I HI
UCCCtSlUlla! hlll~i rj~(' from the pla i n (flnriip(' hil l. lIodi h,ll) hid Ihl'lf '
1<: IJcnrr;dJy ~ I'ry lltlle tupoQ I'aph .lc chanqf' and.1O /"Iwk '/ldc'l' o r' "rlr,
\;:ll l cy rJO~:;I ", 1111' 1,l; rl f'l from r-.;L-S~.J ' rPlI r 11fJo!lHJI' :11111 11,,'1- (1";1 It
i ;HUhul f:ul'. \ulth uf lilt' \;l ll afJC' lh('rc I'; fOlk 111111 Flrl' VI'I'11
\J It rJllt'l IJ !lllk:; ut,!' I" i l e qrilJl Lt tJ"C13'j 10 rUlfll thl' plomif"l('nl P~H 011 11 1""lil
r 1~lfl!l ICI luuu 11.
l<l;;tu.:Jrd' 1111 C'::CdrpWl'lri 1 "'('0I1l{'~ Jl'']:: prtlllllllcllt <llld 1/1 IIlu;rll\ r""I'/'"
ulth Llu' ';urrtllHulinq pla i n.
l hp \;0 1\11:1"" Hlvcr 15 ephclIK'ra l , It cOlltilin~ w<JII'I Ullly ,rlt ,.r 1;,1'1
f'\('"ls 111 !11f' VI'! 5L'OJS(If)i Ihl'f!' IS no permarlcnl l,.tsprJow . Il dr'-Ill': I n
Il l!' 1111, III_r d' I uhr'n' ';1)111(' i', kill d(Jvr1st Il'am , it Joins Ihl' IlmllO!'II,
ItUt~"Ij/" ";l Ill", 1II1 111lIl ;I ';ulJ - lr:opical :lI'lIu-:rritJ ';ca::ulI wIth <;urrun(' ,
'nol r I ,\pr I t illUI ;t ,'11 .. 1 III Y wlI II ,'r rrofl1 Iloy l u Ul' l olU' l . 'Ium, :;1, 1\) 1 I '; 1.11
111'1' 11 I ,
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;'" "u l 0""',',",' " ,.,. 11\1' 1"'111': 11) 1.1' ltl ""I' ''In'l'l .1'1' r" If I . IU ...
•
rJl.l:.lyt·<.l unlIl OCCCIrl!)CI" . the :'0 yeor ml'tan <.Inllual rall,l<tll at 110duJd l
• IS .Iq flUI , Slmllm 10 !";;\borone and IS vr' ry v;lrI<lhlr' . ·;t'HUJd,d 1"\'\;1-
lJPIl I' 12(. film . Ill£' must likely rainfall ',W" prnhdhlllt\ \ J'; !~O() (1111 .
JO"L lkluber-lIareh) to mean minimum tJal1y II''' 'I H'I du{('~, I"~ -lit
I .lUll(', July. AUfJII31) . Ihe daily rnnqf' III I ,''''pr·[;t!IJrr' I'; '11 ... llr·sl
in IJinll'l .
lall f;,ll'I'(j ill 111(' ';umrllcr mOldh" cvnpotr:m<;p l 1.]1 L III i~; 11 111111" ; 1
L:th"pu u' I'; ,lbflUt 20rHJ n,m or " t lft"", tl\l' nl(':II' .H-IIII.J 1.",1:,11. It",',
fill' unl\ uvt'1' ';ilfJll-l'c'riods tloe!> r:llnf,ltl ("'.("",·rh ,· .... ;1110 Ia l 1011.
IIfJurr 2 ~ummQri5C5 IllOnthly m£'DII r<llllf,dl, tcmpf'r:tlurl' :11111 1'\ '1'111 d 101
:\lld f l'1Urr .~ ';ullunan';cs the lur,q lerm rainrall r('rnrrlctl .• 1 tht, \ 111:1')(, .
diSl'u','.ptl rurther in $rction 9.
2 . 2 l.,icljclu lJUrl
Iht' \"")1'1:11 l un u l c:I';lerll llu!::l\ol;!Il<.l has U('PI' "ltl~~lf leLl by cjp
B{,pr ( I'H, /' and IImordf'1I alld Slohils lfJ6J ~::Il .... hl(' Inrllrmill iOIl IS
ul~~u 'JI\"II hy llill"1
~)utll h ul Ull' vlilagt' lhe VCgPt;111UIl I' ; l)llIl':d fir :Icul cq-
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110tlOPl lBoscia AlI.lllrunca) 11oy\llani (qrCV 1<J~) ;]IHI [l(Jrplll;ld !.J~
flCl va) ;Ire corTununly [uund UIl the ~)lllkl t.ih lu ou rr ~;l!Idy ~Oll. llol,'rlte
JnlrlJ!'llun'; ,Ir(' rummOll mid !JIve rl :3C to" {'hLLr;wll'l I,d 11" rt'd 'ol<trujP !.ull
usually 11;lvlna;~ spar~c vegetation of !.Ilurt (Jnl~r; , prrr,llnl;tlll, UIl dccOlmL
ul UI,/f'l"qL\/lIHI by 'Ju<Jls •
. 1,1 1 11 Id Uu' \!llldlJl' li lt' \l1'IJi till!I )!1 C.J\'I" I~, lli"1 Idl"II. 101' ,10'11'.'
UII Ihl' \/,tll-'lIu'IIJ IOl'k!j. ltH' !Ooll J', flUJlC ';;11111" 'PI'\ 10 lull! III rqirllH
:u ld ,:>uPpuIL" a UI'II~JI' :ir:l\l!J u r GdllLJtJ~i ;!lId ',llIilll lIt'!";. 110q'''1(11I0 It'!
mlfl ,l!J;' !;,-'ricciJ) 1:'; tile dumlnant bush ,-Iud IS ",et' I 11'111 [01 [ 'q',If"1 '11
101P'" 11;. rulu (!wll'l'oc;lna caf li£'r ) riu!;plill;, ~t!'I'Ulll,tI Jlllli-jlll'
IlodLJUIJ {t'urntJrr luli l ~.\ ;III\J Iloqollho {~. fjlli.lfl,w1 ;Irr <11,11 l'IP';"ld
Holh lilrlJ(' 11<.1rul;1 lrf'{' G and rl0fjUlIUnO blmhc'l {)('f"u r on ,.,11'1'; I" Ihp , I
cou'r UII lilt' 'J""l1 le-qnL'is<J soulh of the vllla'lf' alld tlWff' 1'1 ,..,\,idl',.11
lli;ll SOliI(' of the L.IILJI' l!tilrula lrees \IIere plwlt('d Ih('1'1' hy \ llLlfjP!
lIlJ5 11'01') f"plu in Ihl' wJlH,tlOU5 .. rpo mapped 0:"; IJatl'rllt'rq ruck-; Ifl thl'>
n1'(,<I UIl the LJcoJu(J1C'al mnp (2 426A ) , Dr111iny CUllfirHll'd qr;J!11tf'-'JIH'I<;'j
under Ih(' ilrt'iJ h;I\'J!II} a co l1u v1<.11 cov('r of 'IIIf1'<.Ilht'I-('I) IJr'Hlll""-'I"(,1~-;q I...I11r l
Illcluill'tJ \Jdll'rl)('r'l fl<Jynrcllls.
j l \ISIIr-...L WAIlfl SUI'I'I Y
3.1 Inlroductlon
l1uchud1 vi I!aCJe \:,fa!) or.rglnally cslnl.d ishcd III 1871 \/11('11 lkl';q.rt I ..
mu\,ed f 1'0111 l.he I rWI!w .. liJl b,ecause of oppre!3S1un by Lhe boers . IIwr(' 15
CVHJt!Il('(' 1101olc\lc1' lhul lhe village :Hle \Jas occupIed In alone Ay,.., i-Hld
1,011 1\'11' I I lilt'!; IJltllmtrly Ilf'ctlusc ur 11..3 illrult'{jlC pw;jlinn ;!I III <1\,;111'1-
1.l11iLy of walcl' . (G liIIJ!. 11)0.5), Il is <:tllllosl cClLtlln II1:d tile vJ11;1')('
•
..... u\cr sup!)ly in c:lIJy limes wuuld hHVC ut'I'n !;upplll'u Ily ~;llH llou hand dUI;
vpll~ III lilt' valky flU .... uccupictl by the r1J!;~;lullll()';pi';-ll uht' I I' U.!lf'f
I, , I
1111' P t rl lit'!;\ I('cord ur bUlchulf' drltllllOJ III ttll' \'III.tlll' 101 V.tI"l
IllI'lro flll' H(lV l!'(,Hllh 01 mO f r ttHUI (,I) tHlII'h()If'~; drlll!'rI IH 111" \lltlljl
tl I rj
for tl.f' tlll'l'lt' val.· ( supply.
al leasl 13 iunchuic!; (off i cial numbers, 3~, 5U, 71)'),7',_. 11'.1....
tu 1111' [11';!;1I1!1 llmijlllal. the olhrr hltJh.111 thp ft.!.;;!k,lil'J" \111,'\ lhouqh
111 fllll'! aIr rl',t'd fill publIC :.upply . Ikfrl\r' I" " 111111\ l·IIl;1I 1'1 [!'hn\l";
ut're tJC.'nclully equIpped wilh dic5l'1 drJI.'('tl pUITip:; WHJ f~d <;';IIIPII,r', III
llll' Imnlcdwtl' ViC1I1ILy .
IhelT loIiI'.; Illtl" rcLiculatioll. folLolJllllj !"pcol1lmcmldliun': r':1r\f' l,\
hole:.; J!:J, U~O. 70? IJul, 1668.2784,2786. 3136 nud ,SIH veil' llllkpri
tu il l'ol!!'!'I,'" mUIII':, ulld a hi.yh level ~torafJf' lank (474 n,'
Oil PIIUlh;Idlkn!,u Hill. ~land pipes 'oiler£' pIH(,C'l.l ~{l !Ilut all 1)(>UI1I(' Iwd
tHee!>::; Lu [I 5tand pipe IiIILhlll 400 ml'trcs. A ITllt lul IIUtllpi'ty Ulltl trC'att:1('nl
\illJlk:..; Ill":"; 1I'I'OIlIHl""d,',j ':outh ut Ih, ' 1 1VI'r 1'10'\' tn \101'1'11111,' w,n but v~rs
.. • .. • • II
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1,,1 I 11,,' rlt·;1 I EtUJI tllll
IloII'hoi,' (h1011111' dIJ';LIHJ l'qUlprnL'llt 10/<1'; reromfTIl'l.dpd \l) l~lllt";
'Hul utlll-, VI'If' tll';\~lllf·d Il boreholc 050. 271lll , ."!I(" jl16 ,Jlld 1\-q but
tll! If' ,1111 I",ronl U1Uf'rJ.
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III (I'r.l .,LsI fdCIIUI, -----
'If" 11" JI'I','II If".I If W.,let Affalrn look O\.f'1 tht v:d"11,10rk<1
"" p,ul.,II,IIIIII:; III 1'1)7 dilily ff'I'ord'> of Uliltf'r pumpeu , 1'1l~,+" I l,nuI'; :,,1(1
,'lfl'lHIf'd 11111" 111'('" ~I'pl <'Ind tC"q'llnl ('h('mic.,t ar,d [·.1' il'llnlufjll';ti
I., .! ill " I" I I I 111 I. r; lt) 01 1111' I'tant jlll'!; 01 10/;111'1 111111,,-01 I1 'I" • • rp\f'1l ill table VIWfC al)~t[a("tlon 1:3 ~;E''''' I I "
I " I" 1<·' I I I " ',', I (J 11' III 1978 lu 246UO_~ m' III 1~1B2 . ~'IVlt11l d ddil,
oil f ' .I'i' .. I}"trill t Iflll of ()I~ rn' .
I'PIIII'1I lu"dul]f' 27116 ilnd 3990 \II('r(> rml 11111<;(>1 . rOI1"tlmpl 1011 r iqur('s
I filII' 11", 11"t:IJtlllt"td ut \/;dl'r A lrair!; illl' !;f'1 LI\ulllj';l(ll' lilt, al,~;tl;llll""
I"l ;llIill)'.L~.i o r till' mOlllldy t(JI'll~1 ',l1ov~; Ihat lIhsl r ~w t io" ]'; 5 1fJn i-
II;"d I ) .pt'a lt· .. In 'il'l'l",uhrr, Ikloht,f' , NIIVt'rnlwr ul'cI Ilf"·PI,,tIPr r1nd is r"1Jrh
IUVI 'i 111 .1;lIn'; 1I y . 1 dHu;lry, rl:lrrh. I\pril and !lay. IIIi 5 lS t;Ulpr151nlJ 10
,
• • • • • • [IQ
• --.. --
\1I'U o r tilL' Illyll meal! tcmlJt.'ra lurc:.> dUl'Jng lhe!;p monlh~ . Ihl' mt'JIl monthly
Llb~tra('lLUfI ove r the pcrJlld 1979-0Z ( vhit'h avoids lIll' l owe r ui<lscd l al<ds
o r JlJ7S) IS ';hO\oIfl In I Igure 4 and a facto r responsible 101' thiS reciuct'd
I1IHJlat l Orl of pi lr! of the I'opulatl{m l u the land .. and thr rall\(' po·;t .
find the pu:;· ;i llll.lv uf ;HI ,,It ' 'ILlil li v(' vIII" ':1111\11\ .dl'" 1 111,1 , 11 ' ,1111-
va/ P I' , L 1 \1'1 Vd /I 'I ele ) .
o f 1('11 ilt IbiS 11"11' J"('n'lvP \'Isito r s frum o t her \,illLHJ"s <:ill 11",1 Ih,· ,"h;nl
V<ltt'! r!PIIJ;u,d \', Ilurrnully ",,!luced durll1!j the 1I10\;ll1lY ';('<I'lOn iHlfJ In, ' lpd ''''',
111l1III'1 ,,',d ('11,1"'1 . . ,11'1 Ilt' lulwl.
the \Jut(' , d('mand m;: ,y no l r('dun' as unllcipolcd and qrci-ltt' l dt",;! rart 101.
viiI Ill' "(,(,pG!;:![ ",· ,
thl' 1"'[lnd ', . "pt"ll,bl'f In Op('pmber. Il IS aboul J.'.I~ 1l1 '11"'r IIoHIl 11" IHII):I['I.
t u SeplrllllH' f dem<!nd , ~lI ld about 20°. hi gher than the Yl~ar{) m('~In ,
- -I , 'C'ar 'If 'Wl Dallv Ah o.; l. al ion ( '11 ',)
'l'u r 5epl -l)(' c . Jml-',cpl •
I 'lif] 400 690 JUO
19711 660 790 6UIl
{"UU (d}1I '100 (,lIiJ
{ lilt 6,0 7:,:.. oOU
l'llll () 7', 700 660
- -.- -lable 2 : Ilpall dnily nh ', ll ;u-l,ulf. Hulllllti 1'11ft _I "HZ
•
U. l .', [11J[choll.: top cle\.<JLlllll :.;ur\l"l')
.\ I 1'-;1
uf ',U uI·I! lup l'lev;.ll llns I~; YIVe!1 i.n ltlC ApPl' ndl'l . ~Jllf'rp lHJlcholc~
hdVI' 111111'1' 1 liar I /"11' ca~lfUJ IJI'jcrLf'd [hp rlevill ion fJl\'CIl 1'3 the Iup or
tl'l' :;II"dlc~1 1~ldlll!'If'1 C<I'.>IPtJ '
" , flotH 1"IPI. 11l1' (,[,'\':11101, or Ih" {poll/od ;1111,(1' 11 IIH1 dU'Jupll<; V<l'i
I"',' t
.1 '11 :,, ".'t ;1 "
1,,1 "1
,t .11 t I
('> r IU .. 11\>1' I d ')U" \; -I)() I f'l1 11/1' 1 r) pUlIlP lily I I";I~; UI'It' (111111111 I t·d
prllpl' rl It'S. 11"lh {"flrl';';u,1 rid .. ilnd ',If'p_rll;l\~dHurl 11";\'; ,I I" ... lUll d ~U III 7/-111"" C'1I1J'.>ldllt r;II,' 11,,;1 !I'dllll :111 ,'11'1 I r I1
,,'
• Q,
Ill(' • dl ';I'llilIIJl' I;III~ \j/.I'; IIIL'~J!.iUrt',J USiIHJ;l CQ!UIHCII'lnJ fJoulllclcr or by
I I J I 11lfJ ;1 dlllll! III 1';Jp,wit). , .. Ihp II"d PI'IJlI'fIiHt: {If 11-dl'[ 'fC"lit, \.Id'l 110] Pili 111'lv
tor 1111' Hl;Jl~':I'!; 1'111 I ff'[ I'I npl'!"! If'" I t~; In; , 1/1
• I tll Ilt'lp i'llaivsc till' :lljlllfl't" prnJlt'rl 11"; ,UH t tll jl1\.I'~;llld~lf' Ih(' l1
1111' \ '011',1.,,11 f,lll ' dill.! UI r" II I :d~'.I'rI '1'11111 Ill£' It" [', 11,(' t hud ;!rd
11'\'1 hod. 1111' !;If'll IJr l vtJO\J1l d;,1 I WCfl' ~flal\':f'lt hy rnrtl"ld'; JI\I'11 1.\
Un'n'lt'1l (\')7';}J I tlpn mul Ita7!' I 1')7..$) Hilt! 1I11'fsdwnk and lhl;'oll 1')61) ,
(It)'wn'l li UlI \IIcll', urrc used fll onl y onc :;1 11' 4..$U'.J ) vh('IP Cl r,II,'I\
Ctlll!llan L fdh' I p:,! wtJ!:i run by Gf'l)loqic~ll 'ill I \11')' ,
H. 4.l I'ollsl<ln l ItIlc lr'!.;l!:i --_ .. _ .. __ ... ---
Ivcllty-om,' JUII!.lulIl fute Il':lts \.I1~ f P V(' I fttt'lllcd ",ul a SUf'lnl;l f V
ur I " !3 1 rf' utllln I'; qllJ£'n jn T<Jb ic 12 . Ol' la ll';!l f il lrtl\· iduR\
ll",\s IIlCludi lllJ the slep:..drnvdowfl tpS\IIIIJ :LIe l}LVl'11 III , I !JcpflrHlc
Il'purl (I;'j/IJK n/~, US) wile re all unUGU;JJ uq u 1 r t' r ft'SPllf l'it' fr om ~;lI'I'e • Ip' ; I '; I' ; .1I";I'I'IIIl'.I . Ii
nl BU I'chulc )~'JU
lIurrhulp J99u li/as lesled by Wale r Arrairs on 9/ 9/ 82 ror
"U hours or dn~wuow rl and J hours or recovery. The purnl1.ing rale
wrl!1 1~.6 m' / h. Ihp drnwdu\lIfI m('asureRll.'nl~ orc unusual blP.c ause
11,, ·\ '. I'HW W;ltCI J[>v('J IlPvrr chrHlyr. 1 /'tfler JO IRJllules, alld lIlP
r"t:u\lI'ry water Jeve l was 0 metrpo:; hlgllcr lhllll lhe prc - pumping
Icvrl. file 11'('llv"ry /1'\1"8 '.1 111 ""1.1, ' ''.I1'l mnlch Illc drowdnwn '10 thr
'\C;, ,>u r P/I'\t!. 'ls ::+ 1-" ohv iUl)4i) ·UJ·,pi'>r!. Ihere lIIas 110 opportunity for
11" ,. 1J"I, ''' ' I '.'. I 1 " I 1 ",
. uti a !;I'IIII 11'4 1.IIIl nl lI'f> dr:~w,IIJ"'" '; ... " , .. I , " I I 'illl" ('( •. It,. r ffp c' of ,,. q l in,! '" i I t, I I' . .1 'I'
' r'"" Ihp " .. a'lul .... menls "oft 11'" '1 1", .. , ('_ ,,, to ... ' ,..01 1' 1 '1 1Vf' ;. [ \ ,Iul".
t" HII bfJr.'I'II'Jlr·; It,£, IIlIlrl 1,· ..... 1 wa'; ,h.I\II1'oI· If" I " ... r rw "",I' ..... ;,bu\e
I '.JtnV SUC ti," nf'ar lhe tlOltom or the hule cilll Iflg testIng.
""lIues . e r. obtained however from slep-draw.hwn tc~ting.
() lktretx. l c 42 .54
I ransmi sshd ly
At bo,.-.hnlr 42.54 thc ) i f' ld was hlyhcr dl1d suf ficienl lhat
waler leve l was lint rlrawn Ilown to pump sucl lon. It was tesled by
W,ltcr AHa,rg for 40 I.ours s larting on 21, UI .'198).
f)1l:;dKI W' fatr v:ricq frum on inltinl '~7 m' / d to 272 m' / d
FI' ar the efl,1 of 1111' llsl. Uecnvery wa9 In('rI!,l rred for t hours only.
I lle early s l OS)c fir the semJ ·log flra.down fftf'iI ' urclACnts gives a T or
11 mO / day. WI~r, ~ Jrowf l!Jwn .. as 14 m COrre'3I"JIIIlrty lu a PWL >46 n ttoe
I le m(' !"iun'menls af,. IIOf r alld a final slope
trortsmi !JslvlLy l' ... noL be ob aincd precisely. 'he Icvelling of water
•
I I
• • • • • • • • • • • • I
• •
j -; • • , I ,
B
CIf/
-t-
T ,
,._._-
. I. .
-'- -1 -_ N '"
~ ,
lev!'i from 400-900 minute9 has no naturrd explanation.
!he early more favourable slope could be affecletl by
welJuore slorage (WOS) .
WelllJore slorage is satisfied Ulhen ....
Ulhpre lr = I \Hlr after IlIl1i cll Hn'i j9 nol Hpplir~ule
rill = well r8rijus
-= tr:Hlsrni~sivi ty
A minules I'Qu id be arcounted for hy \IIrllborp ~;t IlrRqr .
"f I " d Irslil1g ( 18 m'/d) however trAn'1mj~ ;iv il y oulaine\l rom S "p-llri'llol I 11In • mHj!Jl·ql' IIl,tl 1·J1\') s lwuld he sat \'1fjpd willl!!1 20 ll'lnllt ... ~. fI 1Il01P • I · fun tlH' ,·nclcase in drslI/uuwtl al 20 minutps is Cl likf'Jy l"pl<Hl;' . ~UI1 • .
1 t . of thn uppel 1I/11tpr 7{11Jr ;1l1d,lthi~ WrlS l rllrr p~rtjal 'cUla ('rlnq ~ • conri r!lled by rl,ow-meter J igg ing . • d) norclloIc 4266 • Ban'hole 4266 IlIAS te ': led by Water An !.irs ror 48 hours on
4/U/ U). rhe ,lrawuO\ull n,ea' ;u remcr!ls we r e ;Ill !in unusual and are 9"0\;111 • 111 r lIJurc 26 <!lId 27 . 'The rinel yield is lj ven as 1. J m' !" yel the
lo r ehole llad a promising yie l d during driJ iny and the early part • ·,f pump b'stiny .
. Tlllo 'xplonations f or he drallldown a r E' poss i b l e . One is tha t
I esting d" lIfate r ed the nlain 701le . I nGpectirll' of the test data
levmds 1I,Ctl 2 . . 6 rn~!h was suslained rur ') Iluurs unlil 1If8ler level
• • 1
e"'t·..-< ~ ..... ~., .. , "., t ...... ,
'~--, -- ._.-.-,~I.~ ____ --~ .. , • • • • " .. ~
" 11
v
" .~
,~
" ~
."" . -I 1 ' 1 I' • I . . ., ..... I .· ,. : I," . .. ..
, I
; I! '
,j t
-'- I.
, .
Figure 28
. '
• • • 1" ' , I . •. • .. " •
, " " : . , " " L
m ' '
l~li r, ,I , , 1
, " ,
, 1
" - ---- - --- --
, bo._I • • U (~ .., II ) . . , . . . . , . .. . .. .. ' ...
, , . . .. , ...... ,-
r
, ' , ' , ,
Time-drawdowl1 borehole 4258. 4345. 4346
1-
I
IUlldltllJlhupruttUn:CU lllullllllflu ..... Ilu'n)olllllJlIlll II vI'I f',1
l'u~Jldly Lu pump Quetioll and Illp dl!IChorye rule re i J 10 a a~Jslf'jJrI~d
1 .J m' /h. Ir this is correct I hf'1I thp 1l,n>(JJnurn IlIfl"\II JtJ I.S " " 11
I~ c,lm'li urr . III;Hlk I::Ind !>Inlt .. d Crt!'Jflq Vl' rI ' Ij';"r/ In 1,",<;lll"II"
;)11(1 fC'rPf('tlCl' to Ihp (letull; in 111(, Apl,pndl'
I t> "'lome uflc!'rL:.1l1lly by the ti,-i.ller wll('J" 11,,·
11 i:.; POt>filUI" lh .• L Llle jn f' .';pr! rlJ;1\ In'lll ,I
a Gl'c t lml 01 blwlk Ca~IJlI/ . "n 1\' Irl';P"1 llt;I' ,. '. IIIp
Oordmlr. 42' .. U and 11345 .HP ~ III ;)jl;;rl "1 Hlr,l \oIt,,;I o r It·(, I III
• • r oau aboul 1U lUll I lu r L!! uf llochudJ Ilcaf Ittlol ..... ;lt,lI . ':\It'l .1: It 'I •
uorehole 4250 11135 found La be blocked and it was imposs Jule lo
l ower Lhe pump to tile required deptlt . Ho\tlev~r the pump va!'> • jnslullcd al sltullo\ll depth end the boreholc lesled . 00rell01e 4345 • wa3 laler drilled alongside at a larger diameter lo replace i t.
Pumping tests \ilere carried out et both boreholes . The oQuJrer is •
Walerberg sandt>lone i ntruded by dolerit e. Production is ohtalued
rrom a COlltoCt s iluati on at 45-48 III und rra c lures nt 70 <tl1d
'7U-9!J In Dn'tJ lhe 'Vater level i s al 20 In below surface.
Borchol c 4250 \IIas tes ted for 48 hours by Geologica l Survey at
22 rn' / h on 18/3/03 . Oorehol e 4345 was lesled ror 40 hours by \/ater
Affairs on l / e / 8J at 23 .2 m' / h. Not surprisingly the test
measurements are nirn ilar (figure. 28 ) . A line drawn lhrough the
drawl1uwn dulR givrs a T of 66 rn' /d (1.&256) and 108 m7 I d ( 4)45 )
__ L'LI' ........ ,b t-_hl' ml"'n'1!1[pments do nol form a single strajght line.
• • I
-• • • • • • • 11
• • -;; • ~ -' ! <:
'.
, ,.
,'.
•
-'
• ~
.s
11
~
l!
• ..
••
" -' .l_ , ,
T'- .' • ~ -. r ., . t" , , .
t I - ~. ~ ~ -,- ~ - '. N -1- _I
• • • - , • • •
:J '. ~ 'i ~ . ,
• • .8 " .8 8 T 1
• 1
i :t. • • I I ' . .l ' _ . .:....1: ' I I . I I I 1 , " • • I I ,
I" ' . I ! • , ,
, : t ·1 , . I § f~ I · , I • I t
, • I ...J • j 8 I ,. r I I I
I e_ I ' , I
! .1 I
i I .. ,
• 'I , -,
• , , I' L --'. • • I
I ,
l.~ • , ., I
I ~ - , ,
I I
.1 f i • .j L ,,' " " ' , • •
I ,
1
I I ' ., .'1 , I .... •
" , "
, " "
~ ,. I! ,!I ::t I 11111 • I 1111 !
(.) UAOpo'oUQ _
'U l f' , . II''' ,,/11 ,' III·d, '1I,;llI 1,d, 11. ,n,1 'I
I' I I 11'" III
"I . , >I "111 I " I, 1'1" ' . I I1 t "I I , I 1. I1 Idl. j 11 j.. I , . ''.; .) '1
• JfJ It, I
rD '<t C')
'<t
It> '<t C')
'<t
to It> N '<t Q)
o .r: Q) ~
o .D
c: ~ o '0 ~ ~ '0 I -">
0> N
~ " Cl
U.
lilt.! rnCiJUUIC'ucllls Ill ... Uuullun luylulJ cunl' Il.LL.I~ 10','11 I,"",
which lHl rarly T of 50.6 m' / d and iI li1le dala I ur lJ.6.9 m' / d Brf' •
ohtained IIIhlCh are probobly closer to the real vAlue than the
semI lUI) Illlcrprclalion . flatchillg lhe dala Lu the curve shoved •
tiull further measurements were needed lo provide a bcttf>r f \1. .\
5 - day consLant raLe test vas laler conduc Led al lJ.)lJ.S ( 27/6 / 8) '
nlld at .. pun.ping rale of 57.lJ. mJ / h . Durlny Uds tpgt mensurrments
IIIPII' iliad£' I II obsC'rvoll01l huretlol!' lJ. 2 5H and 4) ." 6 ill r = S m and
)0 rn, from wtlJch lest parameters obtained arc shown hC'lov :
Oorehole
4.54 5 (pump .... ell )
li25B ( ob" . 1111..'11 )
4346 ( ubs . llle11) ( incl Ined )
I r :'JIlsmissivity
25.6
30 . 4
45.0
48 . 6
45.0
52 . 1
Sl o raye Cocfricient
0 . 49
0 . 33
f'1ethorl of l\n"lv'>l !>
Cooper-Jacob
HOIl I t on
Cooper- Jacob
Ooulton
Copper-Jacob
j ' Ooul ton
A transmissivity of 45-50 m' / d is indicaled . The storage
coerficient is unrC'<1 Listically hiqh. Although the early dravdO\lln
measurements appear to fit a Boullon lype curve there is doubt
nrisillY rrom the laLe test data that Llle O(wirer rctlron!Je rol1olUs
a nurrnu1 r odiol flo\il (Theis pattern) . The early 109109 drawdown
(rigure 2B) is not Theis , nor is it a 1:1 wel 1bore storage , or a
1 : 2 linear drainage slope . The 10glog plot gives a straight line
up t IJ lUDO minuleB And Lhe semi 10C) dala rorm a curve . Such a
rC3por13e suyge~ls linear and not radlal now . A plol o r ft \lerSUS
lJ (rigure 29) (jives a stralghl line vhich ru r ther Guyycsts
linear flow .
.. • • • tJ
• • • • I I I I I I
J
•
• • • • • • • 11
• • • • ,
ill
"- '--_.
• 7
Ihe' lesl unlo for burehole £12)0 \IIL'('(' ,d!jo UlliJiY'd'U L1y ~ \ AI-.
usiny a melhod more appUcablc to fra clu red AlluLfprs . lheir
analy~is based on an improved fmJial flol.il rnodel \IIlllCh accounl"
for lIIellborc slorage and skin effecl ublnined a lra'lsml"';i~I ! \
of lGU 1nl/cl rU l' very eddy {bln ,111(1:\ ltIotP IPi.di~;tI[, !;\ o ra 4f'
(I_~ 10--2 ) .
a cvnLinuinrJ dravdourl aL late lirnp~;. Ihe SOUI(' rp<;pon~;f \', '" l ,t"I, 1
al iJurchui(' 444U 111 the sDlnc fUl"nl;lliun, WHJ ;11';0 in lp'it .... :Hl'l l \~"d
thcrf'forc be prc(hrted for boreho le A258 by normal Itlf' I '; I I·pt ,I\ .
A plot of ur<.ludo\i,/n versus Ft for borchole 42)U Inu t -; t u t vr1
uhich glve8 a slraiqltl line, indlcales a I-venr dl<1'01duv!1 of
21.4 rn and a 5-year drs",do\lln of 42.7 m <It. 22 !H'/h . llw !';'.'III' pInt
for burcholc 434') er Il)urc 2q) [I ,dll' OItp'; t.b:d t,i Jt' hI" ,.,'1 1";~;I\'f'
and Llle borehole could only sustain this PIle for 6 month~
(s = 78m ) . It 19 suggested therefore lhat a pumpin~ rale of
",..sO m)/h he uSfd and \;later levels Ghould be monilored to provide
data to assist modelling of this aquifer response .
I 1
( - -L r I \
I I
I . I ,
• • • • PI
•
1"fI
III bolh ruck l ypcs loc<l l Cllh:.anC('II)['n l uf pl'rrue.-.LJilily I ~~ nolerl
close lo dolerile intrusions where either prc-c)(isllng strucLures
occur or where baking , bntUe fracture and the development of
p:.a ra siLic f racturcs has occurred. lhcrc 15 ev idence lhnt such
fealures occur at a fairly ull .Uorln elevHtion \IIiLhin the rcyton ,
lhey arc not extens l ve , but t hey are locally i mportan t.
A di !lcrelc (jluund wate r fl ow in c hanne l s regulated by fra c tures
!ILl'; ~;unll' ill'pll(':ulltlll~; fUl uUfPliu\c !JllaClIItJ . III t hese ,H.ju ifcn; 11 15
not unusual for more drawdown to be recorded ut dis tant observat i on
.... e l1 s t holl in \;Icll~ c l oser lo the pumping \:Iell. lid s is due t o t h e
bcLll'f 1lll'aliOll In the ch.-.nllf'\ of till' "1(1("1 di';l;}fll uOfellojp, There
is lhcrerulP a c111"f'('llon,d r'H'lur invo!u'd If ':P<l('1!lq lS ~r(Jperiy
considered and wllcrc lhe ~l~acillfJ is lIot d. ilbcruteiv {IIo!;!'!! ror SOlne
other rcanon such ;jS la preven t ovcffJl'UZlIHJ. An illlernatl\1e \liev In
IOIJ-Yle l dlilY oqul ff'rs 15 to iynorc tile Yl'rlPrai quide li llcs for spaciny
because lIl£' barellolc is such an inefflcient structure anyway and
1n0rt' titan one is prcferff'd to abstract woter ef fi c lently. locating
horehuiP'l ;Il l~C1~;t 300 m part (a standard practice) in many cases ui 11
rll i !,fi lhe walcr-hl'n riny feature altogether .
U.5 . 4 Haler lcvt'! flu clul:I lions
Automalic w;lter level r ecorders were set up on borehole 4234
( granite-Ylleiss) ;llId 425U ( lJalcrbcry ) lo provide a continuous recurO
of water l eve l Ch.trHJ(,~L Purl o f the record i s nhown in riguCl ' 31
vhere iL is neeell lIK1t tllcrl'l is a !1cmi-djurnal ( l\lli cc-d~li Iy) ri se
nnd faJ t in \IIaler level o f up lo 6 cm. lhiq is due to barometric
prcsnUf"t' c hillltJcG :IS Llle (urve for barometrj c pre~!>ure ahows. The
irrcyuIar rl ~e and roll jn \IIuler level 15 dlle to longer term changes
in lhe b~lromclric prc!.n.u l e. This flucluation is a well effect and is
nol occurriny in the uquJfer. It is apparent that there is very
,
• I~
• • •
lilLle net change in le vel over the period of record and .it is
intended t o ma inta in records over a full season or more to reco rd
• Uw fC'plcni,,/ll1lcnt (if any ) and depletion .
• Ihe barometric pressure trace (inverted and expressed as cm .
of ualer) in riyure 31 shollls a maximum change of abou t 10 cm . \later
D l evel rluclufllions much in excess o f 10 cm are the refore unlikely
to ue barometr i c ef fects and are more likely to be due to earth
• tidc~ or lo pumpintJ .
• InGtanlollCOllS change s in \:Ialer level on IS <Jnd 26 I'-lay and
! 7 June ,Ife thought lo !Jp due lo cli!;tant c<lrlhC]uakl.'~3. !he £i cm
c hange rpcorded 0 11 26 t'lay jnlereslint.J occurred al the lime of ltH'
1:'II'ge earthquake at Ak i ta in Japan .
IhfJ slaLic vat('r levels mpfHHlrC'd Rrter drilling show that the
walcr-lablr is v('ry flnt And gO il i" difficult 10 :1ppn"' lalr Il1r
dlrpclion of grollndlltotC'f now. These 10111 gradients and the
transmlss l v dy of the nquHer imply wry lilt 11" lllroughflow \ilhich
in lurn SU44E's l ~1 that till' ml'dfer musl bt'llnvr Inlyply H'l n 'iturnqC'
rlf'V8L i ull lWH'onf Illl'rI rtquifc l ) 1t 19 pvid('rrt ItruL UIl a large Pllougl r
sl'ole ttlPY wi tI Indrc'atl' n fluu direclion which lIIilt u(' the' same <'I"
p.tlII"'loI '; :11,11 1111 f luw I S e'tpccled lu cru:.~; d fr<'l('lllre (r't("pp' pn!1sihl\
C!HHlh tllf' lJ\.IcrIY11'fI uc'alhcrl'd lUlIP).
I 1'I\lr(' !lJ irrdil":rlf'" thal tile ior';d 4rmlllci llIalrr flov i~ inslead
111 .... N\~-<jl clin'! I lUll wjlh a qround .... 01f'1· divldf' undC'r lhe hiqh 1.111" of
Ihp f'!wHfprnf'IIL Qrp;1rilUnq fluw la lhp NW' fr om one towards thr
\·, 11,111'" 1\\ It\(, foul 'lf the I'scarpment in the vi ll agp therp i~ a
(jluund wHlpl di"C'i1nr'lf' :1rrH wh il"h :lrColHlt'1 fr l r the higlllllHlcr \pvpls
<Jnd till' numl pr uf dU{j\ll(, I Is J rl Umt are;"! . 1I i~ ohvfu\l~ly one of 'l1p
rl'f-l~;orr~; r ur Ihl' parly :,pll l(' rlll'lll or the viIIHqe) .
IrqufI 25 drmonr,lrAt.p<,; no ohvious fJtJ\1I direction bf'caus(> the'
Ilmtpr If'vr\' nrf' vrry flnt nml smAll cliff PI ('flI"P<:; in Ipvrl could bp
('xrrrd('ci hy ~urvpyjnlJ rrrors , hut I ikf' fiQllr .. 2lJ 111(" AfPA i~ P<'llt of
(1 SW to f'.;f di f(' C'Led ')ur face rlrnintHlP f1l1d 011 :I I nrq(' qCHlp thAl would
b(' the {'xpc.·tmj flow direction.
§ Ihe steHdY-!3tlll(' Ihrouyhflrlw hptwrrn uorchole 4 19H alld lJ2J4 is S.B rn'/d (20 x 1 )( lOUU) 39sum i ng an aqtdfer W1dth or I km. This
1S equivllcnl (GU~ IQU rf"'clwrge!yenr. II' you consider the aquife r is <lUUOIII IIIldr! ',;,y SUO III tl1rn th~ thlollqllrJow j., nrq liqihlc ).
'fI.t
Water sHmples were collected from the most promising boreholea
drilled and from many eXIsting boreholes 111 the rcglon for chemical
:m<llysis. lalllu 15 summarises the water chemistry of the borE-holes
elfJ IJ£'d and lable 16 summarlses chemistry of aome existing boreholes
Including the /l;oL"'flne river .... ater in the vi] lage . r"osL of the
C'ltistlntJ lJurr>holc wnlers jn the villaqe Dre modified to fI greAter
n[' Jp' ;';!' 1 p .... I('nl by the effects of pul1ut lun so that th{' frf>'3hh
drlllpd uorf'huh' \ilHlcrs in h:lblc 15 arc mOIC represent.atlvE" of the
UlIIC;uIF·d a'llIilt'1" ...,a ler.
[t i'l Clpflf r.llm the TRLJlc thl'll thf' \oI;llf'I<; have rnodpratl" tu low
Vl'dC f9 fron. thp t llrre aqlJifer type~. CJn('js~, c1nlcrHp or '3omi'3tnnp .
11 ,,, '.ntI'S'" :, ... ' 111 rlf' rally domulalct! hy lilt' 111J ;tlld Ca ca llOUS and by
1hp lov 1U'i ('ontf'n l ond !.imi lar chClnj'lrirs of :-tll the w:-ttf'rs is
n tefll'dlf)ll uf lite generolly chelnicHlly i. ,prt oquifer malerial and
1111' I ,wk nf m{)vl' l<lprrl willlin the Aquifrr. PI(' flqulff'r mrtlpri<ll fnr
;tll \J"'f"'~ I': Illl"lulliy n c l·y .. tniliup I"or'k If !. ilic-<lte lIIinf"rfll.,. Thc
rilrmlldl ('\.'o)utwn of till' ground wFller io Irqely c1nmillatrrllJy tilt'
\Iwlltller IIIIJ prUI'{'~:" and motu['e groundvnler wIll have B compos jlion
If'IHIII I'I 1(1IlIart/s rquilibrium \I.rilh the varlOU·1 clay mll1£'r aI5. Thua tile
(".1111)11'': PI''';f'l1t on t hp yruundlllalcr are I!H<,! " ly lhuse releo!icd during
wealher lIlrl of the primAry minerals preselll and their relAtive
leClcllvltlen. I)iolllc is of dissolved Uy 2.
le Alld K. a source
1'''111'('11(' flf C02+ lilt! My2+ and plaqioclaae of [1/+ nnd NfI+ .
Ihe duminant [Inion in the unreaclcd, rl tlshly drilled waters 19
It{UJ
, AlrnfJ';1111C'ric CO2
contrnt i!'J '\.U . UJ!. ;11111 lhi!> i9 Hlcrca~ed up lo
100 x In till:' soi 1 UIlC lo root resplrnlion Alld decay of 90il orgAnic
matlrr. Ihe eJtf'ration of siJlC"ale mjner!!l., to c lay minerals in the
.Ill '1
• • 8 I I I
•
" ~
wcnlht"l'in(J lone also rclc<lscs HCOJ
_ rind 5iUZ
so t/mL these are Idyll in
vatero ir,rilLraUng rram the surrace. UicnruonRle is thus very high
to hlflh find in onolyses rnllge:J rrom 101-717 mg/I. SiOZ
js a190 high
;Ind rtUIfj('9 rrorn 56-116 rnlI/I, with ~I iqhtly higher values noted III
water'] frorn Watcrbcrq rocks.
Ihl' ( l'a 4- tlq),'HCO J ndios 111 Tnhlc 15 And 16 demonstrAte that
carbOl1otf' cqui I ibraum is achieved lit most waters . the RnAly!'ll';
stlOWlfly (C lI + fly)/IICO, ['dUDS »1 demonstrate Q flntural evolution And/ ti t
+ pullut lOll toward .. jllc['rw;lng Na I NO
J and Cl ( borrhole 4234, (JUZ,
4232 and J'JtJO) . On fl tri-linear diRgrorn riqurf' 32) the waters Dlol
III difrCIf'llt r lel d!) W3 illl/lcrlled . 1he diagram H!'W 'wJ,Hlralps Ollt
425411"; hlqh Na"'" ;Hld 11[0,-, and i~ !hp unly wnler llIlth A (Ca .. r1ql/N~
rallu < I (0 .72). the prr'ff'rPldllll wpathrorlnq uf p lng.LOc1ase lo
lel£'a''I(' No" ut ion-e,<chRIHjr" i'l a likroly r'Ol1ltol of lhi9 c-hpmiqtry .
Ilurt'l,,,J,' 42~? J'1 '101111'1111\.11 'JlUJ'.wll I' h:lVII"/ d hlqll/lltlil!f'
Irwall'd III d flf'lll. lIorkqrmmd nit/nil' l"vf'l., rtom ad.l;}('cnl drillilltj,;
lonc-en! rOIl 11)11 III 'Hli I IlIn • .,turf' mid r{'molli I i:.l<r t iOIl. AppllC;tl HIll (If
ferlllll'!'1 in rull'UlJul . lIigh IndIYC'floU<J njlr"l" I('vels or up In
I UU IIIIJ/I uI,rel<Jlml tn I)olluli l)fl hove hOlllclcr n'cI 'lllly been n'IHlII"rI
ltl K.I tuhall salld~ {!lctltan, lallllA find Vu,,.I , lqO J nn Iltal a
{"Oficelllrutlull fa c Lor could be re:::ponslbJC', 'lAmples from d,rrell'"l
dqJlilS in IHJfeholc 4LJL dcmorn;llnll~ .11", It ,-/11(";\ 111\1'.l1c ;III(} ddutldc
J('vC'l::; urC' al the lIIolllrluble dccr['w;il1g WIll, df'pth t:uqypt:1 lny fin
InpuL rl'UlI, the ull!wluraled 1'0llC wilh t>UIIP dCl1ilrjriniliol1 ill tJlf'
!..OatunJLcd I'OJlC. fhe flil raLf' l('vcJs lIIuy also be JJlrlucru,;cd by land u"e.
OurillY LcuUny the waLer' qunlity imprnvI'd si itJht Iy If; vater \jI<ln beirH.J
taken from deepcr level'l in tile aquifer. (105 169U.IJ76 my/I).
. ,
• • • • JI
• • 11
• • • ,
•
c
Uorehole P-499 18 moderately 80line (T05:::J587 mg/l) .ith
e levaLed Na + and Cl conlent. Only one analyais of this water is
available (Table 16) but it la thought that mineralisation heB 81~8y8
been presenL principally due to the aquifer (aiIt.toue) and pos8ible
later mod ified by contamination at the cattle poat. The (Ca + t1g)/Na
faUo ia <1 ( 0.62) which ill similar to 4234 (n.72). Borehole 4205
close to the cattle pOlt waB not full analyeed but had unacceptably
11Iqh rhloride ( 995 mg/I) and TDS (lSSO mg/l) for public supply although
all acceptable nitrate content (28 mgl1) .
All other ... Illtrrs in Inble IS .... ith eXC'f'ption of )990 (NoJ
>100
my!]) ore nuHablo for domestic purposes . No element i9 present In
d;HlyerOIl!'1 tltJ8lllitia9. SnmJ3 further (h .. tail'l or wator quality 9rt'
given in sectiOfI 10 in di'l c ussion of pollution.
H.6 LnlJ.cal Ic viclII of bo rehole SlUng tC(;hlligUBS
Tile lechniCluPB used for borehole sit .lng - review of edsting
known 9fJuifpl'1, tilt' identification of Ilflenmente on satellite
i rnoqcry Alld thl'lI on sir photos follow"d by confirmRtion on the
IIrflUlld l>y clcctnrnl resi '1tivity and m9gnC'tomete r tnwersif19 is A
r.landarll Approac h bul lhe results of driJ ling havo been generally
poor. If it 19 R!'('''pled that lho main IJl I'H\menl direclions are
the main <) l Oullrlwiltrr fialll' channl' lfI 'hell U f' low YleJds typical of
Ilia fly lJu I L'huI '''. SlJ!J4tw t l IIn L lhey prll" t ratl Oil I y the rninor
fracture!) and Im vc miHsf'd UIO m; li ll l ll<mnrl 'l . Uorehole!J locoted in
the cl181t1,els Rt 42 S4 and lit chRllnel JIlter ' ""ctiollq 42,8. ~J4S,
4346 alld ? 4448 dcrnOllstrnt 0 a slrong qr(ltll rllI/nler circu lati nn. other
barchalC' '1 dri ll C'u un prc ~lIJmed intcroC'ctiOl I of olructure9 have been
IC9A !lucl'ens rul. Ihis mny be dlJO to minnlllg tile fe{)tur£' or A VPry
poor tJroul1dwatcr drculallon ..,j Lh.ln bomc r coclurco .
•
11)('I'p i~, irwreasinrJ eVIdence, these drillinq re9l111 ~ ir ll' iurlco
lh~l ItlP prumln('nt lineations and crush-zones are !:!2l always the main
roules for groundwater and groundlMsler prefers a leea-obvious path
of ruinor f ruclures relaled to the mein structure (see Kahul.
fOlllerAk('r eLal. 1983), If this la so it would appear that the
slrategy of drtllinq on prominent lineations is not reliable, and an
analyncq of the tcocLollic pattern 1n the area followed by Relection of
speCl fie JiFl8amenls 13 necessary . Other frnctures were naturally taken
into account when se J ect l"9 si tes .i ne 1 ud inq locat i ng si tea c lose to
drainaqe lines, ("olrsidrring vegetation (lerql'" trecs elc.) ani"'al
indicator9 (tprmilr> mounds) and liIolcr-djvinlllg. WRler-dlvining "'8~ used
quilf' frrqUl'lll1r lu locale Actual drill Ai\£''1 within 8 previouslx
ldl.'llurJed A'Iomaluu,> oreo, tllld gave 0 slgnl flcant indlcetion et borehole
4250. I hO\' nil dfHlllts that woter di vin ull1 18n hp uSE-rul, And an
P"'I'IRfllIIIUfI If uhy thp melhod liIorks cnn be found in sevcral publicollons
(e.fJ ' NCIiI Sr lenll~l VtJ1. 81 1979, pJ/I, 20-2,' December 1979).
In the -iaterberg which 19 8 la yered fl ' ri 'mt lun cerlRIn layer!'> can be
identiflcd a; beltcr prospei.:ls from their phYSical propf'rties Blld
liUlOloIIY. Ihun oilhfltJgh till" mrJ1n uhJecll1c hf}!) been to locote
frilClurllll]. 11tholo'lY is slill importanl hl'l-l(H>e n~'lt'1 control over
tI'" type Am nalurf' 0 1 the I rnclurinl) 'Whirlr IIc["urs do!'!£' la Intrusions
01 fAullinq_
\II1I"'Oml'rll direcLlun', ;rre no! always I lie malll dirl"'l..:llolIs of qrouJlflwatpr
Cl rculEd 1011 ,lnd G:hpr realUll's moy be more irllportollt. Con~ide l IUon
<;h01U lrt thf'n r(He' br !jlven II deLerminp whi"'l linf'Alnent!'> in a givrn
HIP:I :1rI' 11101" ijk('iy In be I roductive'.
It h:1'J'd ',0 1)('I'n found (me fu 1 to p ro!)pf'ct fo r A it es cl ose to
ell dllmjl' ) il ')·r:. Oral! 'IfJC l ilies may h<tvc d. ve loppd ovrr major (perme'sb le
If ;1{ lUI" .fur P'l, I'tll 'lr'rne dl;'ll1nl.jc I irl!"tJ du th'vclup all impermrslJlc so lid
• IU 11 • • IJ ~ • D
I I I I
, .
•
• •
lock "L,Uorms, so sites have to be investigoted carefully. It i')
:dGII 1I~.iI'fu l to prospect for sill's near to rock !)ulcrop . In ~lO mp n r l:";~s
it is probable that the easiest access for waler ro reach a g roundwa ler
body is through fractured rock outcrop and areos of very thin 80i J. A
groumhJo ler c irculation is therefore rnore likely to exiat close lo
fra ctured rock outcrop. The intersection of linesmenta h88 been
demolls! fated 89 an important target where greater fracturing exists and
where qroundwAlrr ci r cu l Rtion from different areas comes together.
Lo ca l rracturlny clasp to the rr,argins of intrus ions has also been
dC'nlOWl t rlJlt~d 99 8 uspful lOCAl toArget.
I )(plo r nli orl techniqtcs II/hlf'll exnrnine I nlf'Jul dlffclI'lI('c'J i n r oC'k
propf'rlies, lncluding mfJellf'lornf>le r measurement '1 , r cs i s li vlly measuremenls
Slid ionduc-ll vi ty (VI r ) or dine l ined borchole dei 1 H ng are seen 85 mosl
apprupriotC' in I h(>or nAno. VI"ltical FlquifpfS.
,.
< •
". WAIIIl RESOURC[S
Ih .. oulrome of this study le that the resources of the fradured
aquifpl" J ol MochU(Ji are difficult to quantify with precis16n. This
should no t be surprisi ng_ The exact dimeneions of the aQuirer are not
kno\il/l Rnrl recharge, which la suspected, requires long term monitoring
lo men911rr il. 10 obtain information for precise calculation lIIould
rPClul r£> n larlje Input of drilling and geophysi cs Ollt of proportion to
the '1('ole of the supply. Furthermore the mosl important aqui fer tests
do nol dpIl1Un9tratc 0 normal Iheis rpqrOIl~e ttl pllmplng BO that the
interprc l"d aquifer l',ojlP tl ips Rnd f orcC'8st drS\IIdown is nol as cerlain
no; it ("ollll! hp.
In fra clur! d .. qu I fers lhere i s no lIIay of predi c ting in advance the
rp,;ponse lo pumping nnd whelhe r the main froctu res will be dewelered during
devclopmrnt or whether recoltmended yields op' ove r-pumping or undpr
pump ing t hl"' resourt:£' . thi s lS IIIhy it J '3 imp'J rtunt la keep Accurnt£' 10ny
tf'lm 11 '10 1'1'; I)f pumpinq and IoIfllf'r levt'I 'i to Iflon.llo r tllC SItuation. The
method'] usrd here Lo caJculal e the rC SOl lrc('s Lllun rely h£'avlly on
:1';''1 Hl'pllllll' :!lld ';l1oulll he v il"lUed AC'cordlngly.
I f thl lIruul lthmtf'r U'SO!Irc('s ar(' n'gard('d AS f09s11 resourc£'s ,
i . e . withoul l'urrf'l1l r rp lefli! .llfncnt tt'('rl the quanlily ovailable can
hf' r al l'ul;} I ,··1 'ruIlI 11 1f' dim,..,, · Illl>r. I1f It, R,,'IIrp r nnd it 'l RppropriAtp
stu rnge pIIII"·rli"9. 11 Inr r, '·'p l ' I' I'~I '; illlj 1tIf' llfJ('ld AQlIir~r
1'1 J O Io:Hl 1(11"I ],V ".~, km wi d£' ( 0 reFl'loll.I,le W'1l1mptlfln) with R
Spf'1 ,fi e yj" d u f I . I Il '-n 1111" yparly ab·.lnwl ion would produce a f oI l
i I. lJat 1"'1' 1evI'1 of ~ m. Thi 9 lIfould hove oceul ,·e<..l enc ll year s ince
produclion ' ;I arlcd :lI1d If II lIIe re Ihl"' C .. IS(, I1 '11 Lhl' water levels l:Iould nou
he 60-70 m 11" )0\11 ~; tlrrflce alld the bon'holps .11 ,dd be dr-y.
..
• • • • l]
• • 11
• • [J
• • It ~
• • • • • [I
• • • • •
•
Ilo\llr>ver it is believed that there is a certain amount or Cllrrcllt
tl'dllH4l-', Nitrate pollution and 8 reducing chloride content oner rain
(B C£' riyure 34 and 35) is Borne evidence for this , and the ability of
the borehoJes to sustain production is another indication. An
evaluation of recharge thus requires consideration or the hydroloQical
processes involved .
9.1 Hydrological processes
11ll' Ilydrolnqir' <tl I1ro(,I""I9C9 jflvolvpd C':m hr stl tJWl'nri<; rd Quit"
ojl!'p l )' . Ildlll 1;llllnq tHt \IH' qu rfn('£, it! Illr runlll,,1 \IIpl wOll th ·; nl
NUIJ (, llIiH'r , fll'l'f'lUhrr, J~HIl'f1r > wld I r!J rU:1r y I n Il!lrlrllUllPd ir l\U rurl-ut f
~ 1I ,d IIlflil,:ll inn I,), thr 'wil amI \IIpR lhrlrd 7{11l('. Whf"tf' tllptt" i c:;
lrlll,. ';roj I "o\,pr, Oil ror'l( ')\lle l'op rot p't(nmpl", wHIf>r mAY r{"~('h
thl' IIInlf'llnhll' rl'l~livply qll i l~k l Y lh roll'lh fr:lcttll{' conllect lOlI O:; .
othcrllli~ .. v:drr I'ril{'r!1 so i l m0 1!;lu rp GllJ rayr . Whrll ruinfall , <>
IlI<lUfflril'rd t o !i:1 tlJ rntc no d mu i s ture and w";llhrro lcd 'oI("rllhrr£'d
/Oll!' '>tormlf lo field rnpAr· i.ty Jit tle or no rtlll-of f or('ur ~ a nd thprp
I': 110 (>'0«(1";'; II1f 111 r;d ion 10 brrome r erhA rye . "f't l"r soil moir;turf'
;11101 11I1';:dllr;tI"d /(Hll' ',turof.j'· ]., ,;ti!'>l"ri tu fi eld (,"IWe ll y hoth flHr
Il lf ,ll1c] rj/mlll,hOl:1lpr IrrirnflJl' CRIl OCTu r <HlflljrOlllldl,Hllr! ' I rvl" l '1 vIII
1>£'(11 11 III II '!' ,
11 11111' ,llllt,1 Ihio; p r o('(,4') 1"1';11'01 T';'lll~p i ln t i Ol t l r; 01 rlr rrl lltj AlII !
V.tlf' l" I'; 10 I flOIll Ihl' '>0 1 1 tu l'r"I' 1111I.ltl. allll thE' aquir{'r lu!':r';
Ih(,sr lu ;~;r'i ('(lIt llflue thruUllh I hp
dry fI('a';(Jtl ,lilt! "lit! i fer \l/o! ... r lcve ls are expccll'd lo rC<tch Lt It' L I"
Itl\l/r~;1 I llIIHPdlrllcly prior 10 lrll' unset of l!l{' [';1 111 '1 ,
lJlIIlpr I hI' pr('vniUnq climatic condilloll3 in Uolswana an ,''( cess
ur wnl "l" "VI'I" ';u il mo i,. lu lc and f'vapotranspiraliol1 frquLl"elllPl1l is
raU1I'f I ;IfI' '10 tktl rprh'lI ljP th rough lhr '1o i 1 cn n h r l"XIl£'clpd 10
Ol'f'lIr ulIly t)(;C rl !;i<II I: IlI y , IO!' rl1:1119 unly (!lIl(' I! twil -l' ill ~: f'\d 'r; d yNlt!l .
•
111 .upa ... where the soil is thin or fractured rock is exposed il is
expect "d l hll t recharge occurs more easily and lTlay be the dominant
pr" '!'i'1. TtH<) rQuld pArtly pxplain why Walf"f l eve l s gf"nerA ll y
rise Bbo " W:'ltpr strikes during drill i ny .
-, . .. .,
A wILer balance calcu l ation la use ful in 9umfna riBing thr
hytiroJo<pc;d processes and in obtaining e st i mAteS of dlfferent
cumpnncnt'i ul the hyd ro l ogica l cycle . OeCQUfiP of the difficulL.1f's
of "P.I'illff'tlll'l l l Hlld the pArliru lor IIrlecrlAlnlH'9 In the cvopoLr<lnr,_
pilRI iUII p"t l!!ml·' alld sojl moistu re '1tOf:lqe> fl prprigp water bAIAnrf'
CilIIIlO l br nt If''mplrd for the nn'a !'itur/If'd . 'i1l"'1 a qludv lIIoulet
IIUI9 III th,' ,";11111111,,,;
WIII,ld "'" 1" d tl.,· \. ,Itl" III IPrh:'lrqr-' nh ln 'lIrd '11' n'f,tlmLl I~; 1";1'111) 111
ljIVII1!) d IjIJ\flp I" Ihf' plobnblp qun"tlli,·'1 i ln IJ\"II . A 'ljmp ) ifil"d
hil!rU1CC IIIr.l tll'rl rOI qrolH'ldlilrlirr l'I'dmrqr i~ ;'"; 'll!lnw<;:
I,r = I' - lA - 6Srn - RO
r _ '" n'<'I11
Ill' I \,),",11111(,' It"lillly Iq in Ihl"' rV;'il' tr:"lll"ll'ilotHul Lwtur.
Aclwll I"' V:tI',d l :III';l'lratlUn i' (lot "ann:ll t y I I'WI1 ';0 thAt it 1911'11lnlJy
11'1 01 ", ,"d h . I {'dJ. uiot,·u onu unt (f'otrlllini I"' Rpatrilnopiraliofl).
1'·1 .. ,01 I Il'lltlll l'1plrn tiol (PI) j q R thl'I >I,'licRl cnlc'uhttiOI1 o r
""f'" 11 I " <./:1' pr 1"'11 I"m bt" rl"'mnvrd hy I r .11":1' i!'ld jltl1 of 1'1'11,,1:"\1 Inll
111111"'11 qurrit l Int wnll"' r 1'1 n\!; jlnhJI' ill Ih" >.fll l 10 ml"l" tit !"' rip",:,,!r!.
I I I [ I I I I [
I
• • • • • • • • • • • • • •
•
CUl1dil i ll/IS , bul ill arid Rnd !>('mi-nrirl coun tri c:.; till' ';upply I r ',pit
moi~.llurc is llmitcd, crops ;ll\Jay~l vlll cllld the pulcI.LJ;.! fHJUrl'
tjft:1Illy C''I(rf''(>d'1 thr" nrlwll cvapol rnll ~pi rnt jon .
PoLential cvopoLrangpi rall on C!llim;:ale9 for 110chuJi are shOlln
Ul laLd e 1 7 . Pull'l1Lial evtJPoL r i3ns~.llrali o n i s h iyllest from
October - rcbrua ry (160 mm/month ) reducing to minimum va lul' ''>
( 40 mm/month) in June and Jul y . T abl c 1 7 reveal s t ha t po tcntial
evapoLranspiraUull always exceeds mean month ly r aillfal I BlIll lhe
probability of mean monthly r ainfall exceeding P[ i s ve r y 101.1
(O .J j) . Un a ulollLhl y mean biJs l s lhe vale r balnncc Lllu"> ne\cr a ll ous
UllY r crllLlryc . It i5 more u!lcful lhcrpforc Lo cun!lider actual
rClinfiotl J Dv ... r s ho rler pcriod9 and lhis hos been done in rigure 33
wherc actuul ralnfall is compercd with PE over Ill-day perlOds
belll/ccn Jul y 1982 and June 1903. The excess rainfall ove r , evaporation for this peripd is 94 mm. (Sce olso Table 18 ) .
9.3 Croundwater Recharge
It is likely that two recharge mechanisms exist. A slou diffuse , ,/
wfiltration through lhe soil and a more rapid infiltration through
fractured rock outcrop. Before di ffuse recharge can occur it i s
expected that the soil moisture deficit must be satisfied. This has
not been measured but has been estimated from measurements of soil
moisture at Sebele supplied by J. Sinclair (personal communication ) . ,
These measurements show a seasonal depletion in the top 0.9 m of soil
of ~ 100 mm. A certain amount of storage will exist in the
unsaturated zone between the soil and the watertable. At C . .4-0.S~'
porosity this would require 100-125 Illn so that till unsaturated and soil
moisture deficit of '" 200 nwn must be satisfied before di ffuse
recharge can occur.
J
•
- ' Jrtrl f' cll 'lilr ,\~ r J lay JUlIC July AU:j 'jq'l lid \u\.· lJcc
; lean max. temperature ( QC ) 32.6 3J.2 31 ~l 27 . 2 24 . 6 n.2 n . 3 25 . 5 ~? • Ju . 7 \ ... Y2 •
flean min . temperature (QC) 19.7 19 . 0 18 . 0 lJ.1 7. 6 " . 0 ) . 6 6. 5 1 J. , 15 . \ 11 . 18 .·
Average air temperature ( GC ) 26.1 25 . 1 2" . 5 20 .1 16. I 13.1 12 . 9 16 . iJ :0 . \ • _~ . 1 . ' . ..... "' - ". -A~erage downpolnt ( GC) 15.5 15.8 14 . 2 1 J. 3 6. 3 2.1 1.!1 2 .. -.. :3.0 : 2 . _ 11 ..
Radlation (M/m ! ) 200 206 182 1J6 lJ8 1 • .:& 1 J 1 1" ! !aJ . • 21 •
IPotential e\apotranspiration (mm) 163 lJ3 11/j 75 53 )2 )6 7_ 119 ,b 1 ~)~ 16J .. .. -2Potential el..'8potranspiration (mm) 156 141 157 123 122 1l !J. 118 1_0 10J 165 .. 53 1-3 r;: ..
JActual evaporation (mm) 17 21 2 - - - . - . IQ c
Pan evaporation (mm ) 293 226 21 4 157 D8 IC6 1" .- 16" 25) 3:...7 236 2JB
'r-lean preclpitation (mm) '96 79 : , 59 39 12 5 " - 1 J 39 o. :':: , 1
P. rain; IPE 0 .11 0.1 0 0. 13 0.1 4 0 . 05 0. 11 0 . ':2 0. 001 O. r ~ 1 , J . ~..j ',; , - -
110 day mean totals (fISD)
'r'lorton (1978) .
'Ilean monthly 1931-82 rloc:hudi i
Table 17: Evaporation CS ti lllot cS. Gu.bo rollc data
- - -~--"- ·- ,", e.
•
• • ~ ,
c 0 • --• " .-
~ ~ m c M g :: • E CO , " en -~ N
i / • u m ~ c ~ '" ~ ~ ,
~
> \ • ~ ~ • c
~ I ~ N • /' • CO .- ~ ~ en ~ 1. c ./ ~ • ~ / 15 0 ~ ./ " " ~ .t: ./ ~ g
",/ r ~ /' " • c: / ~
0 ----. -.. > ~ ~ • 0
l ~ 0-.. ,.
> ."». c " I
• 7ij I ~ , . ., .<:- c
" u -.'l 0 0-
l '0 c
> .. .- 0
.> z 7ij -C - e u 0 ,..
i .. .'. '0 ~ • 0 ............. ~
'. ~ ............ , , M ~ M .---... e . ./ N " ~
.2' .------ ~ u. ~ , ~
{!. ol\ ~ ol! ~ 0
( .. )
-. ,
I r llll' unsaturated zone storage requirlmcnt is 200 mm then only
j I'Cllll evenls during the 13 year period , 1970-83, (1975, 1977 snd
1970) ~cre sufficient to generate recharge snd runoff and only 37 mm
vas available. I r it is assumed that the unsaturated requirement is
only 100 nwn lhen a much larger amount is available for recharge,
totalling 475 mm or fI mean annual amount of 36 mm. Obviou91y
actual DUi! I'lOislure and unsaturated storage amounts Bre needed to
analyse events in thi9 way.
Allhough potential evapotranspiration estimates have been used
in the calculation ucLuuJ eV<lpotranspiration roles control waler
losses. Estimates of recharge using potential rales are therefore
likely to be un~erc9tim8tc9.
Morton (1978 , 1983), presented a method for calculating actual
evapotranapiration. and estimates using this method ere included in
Table 17. Note that these are very much lower than potential
estimates and during the period April-November they suggest there is
no actual evapotranspiration (for reasons of soil dryness) . This is close
to what is observed at Sebele where evapotranspiration (snd
drainage) losses from the soil betvecn 26 May and 8 October 1982 were very , small (5.29 mm ). Leck of reliable runoff dala prevents further
analysis of tile wuter balance but application of this method to a
controlled cetchment would be interesting.
However in a fractured aquifer consisting of vertical or sub
vertical chslltmels it is theoretically possible and indeed quite
likely thot tire quantity of water received by a fracture could !..xceed
the rainfall hecause the catchment area to the fractu re i. MUch larger
than its surf tce srC<l, and under these circumstances 8 water balance
approach will not work. A more appropriate nnd certainly IIOre
convenient mt thod of ossessing recharge is therefore to record water
level fluctualions and to relate changes to an aquife.' e
• 111
• ~ • .-[I -.. .. • • • I
• • • I
PE~I'lAN POTENTIAL EVAPO TRANSP IRATION (I'~1 ) 10 DAY TOTALS , ~10CIIUOI rAO/m15
Jan reb Mar Ap r r~ay June July Aug Sept Oct ~ov Oec Total
I 55 47 42 31 22 12 10 20. 34 50 52 53
2 55 44 41 24 17 la II 24 40 56 51 53
3 52 42 35 20 14 10 15 30 45 55 52 54
Total 162 133 118 75 53 32 36 74 119 161 155 ' 160 1278
Year 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982
Excess rain-fall 25 125 48 52 143 235 140 201 201 117 73 153 85 ( "'" )
Rain [ven ts 2 4 3 3 7 6 ~ ' 4 4 - 2 2 6 4 >P[ .
1 -
• Table IB.IO-day InC,Jn Penman potclltial evapo trullspi ra tion <Jnd excess rainrall events , r'lochudi 1970-82
• .•••••••••••• _--
l~alf'f' If'vf'll't'f 'ufllc rswcrc io!;lull"d ror tlli!~pllrptl!H'orl
borchole9 in May 1903 and vatcr level ri ses were recorded in burehole
38 during November and December 1983 (S events), which will be used
for ca lculation of an aquifer storage.
9 . 4 Aquifer storage
Another method of estimating recharge is lo calculate the present
~el1field abstraction in terms of recharge over the area of aquifer and
to ~ee if the amount is reasonabl e . When considered in conjunction vith
aquifer storage the recharge estimate can be comlJored with vater level
decline.
Only two estimates of aqui fer
for the granite-gneiss aquifer and
-2 sto rage ( lxlO ,
-2 one (IxlO ) for
-4 lxlO ) are a va ila! le
the Watel berg rock! .
It lIIas assumed earlier that the aquifer supplying the village vas 10 kn long
and O.S km wide and if t hi s is reasonable the 1982 abstraction is
eq '.Jivalent lo SO mm recharge over the full area. This is a large amount
(1~4 of the rainfall) and is an indication that current abstraction
is probably in excess of balanced recharge.
If current recharge is say half of the abstraction (25 mm) then , , water levels would have to drop by 2.S m to :Iccount for the \W'ater
removed. t1easurement of water level in borellole 38 showed a water
l eve l decline of 3 . U28 m between January and October 1983 during which
time abstrnclion wa::> 240 000 m'. An aqui fer storage , of 1. 6% or a
r c1uction in storage equivalent to 30 mm is indicated.
The regional water level .decline that occurs under develop/dent in
a fractured aquifer may not be as uniform end predictable as in
9 natural aquifer , and well yields could dramatically reduce if
water l evels arc lowered rcgionally to the principa l inflow le\'elB .
J r this occurs thonc boreholcs having water strIkes closest to
Lhe watcrtablc would be affected first.
• IJ
• • • • • • tJ Ii Ii
• I I I I I I I I
•
'3 I
As a provisional estimate to be modi fied wherl dala becomes
available, recharge to the aquifers ot Mo~hudi could be within the
cunye 0-20 flu/yeor (O-4~~ of ruinfulI) . In ally cvcllL it i~ riot
likely that a limit to abstraction could be placed on the existing
supplies from the current knowledge of recharge. Development of
the aquifers to the north and south of the village should be
monitored in order to obtain data for such an analysis.
9.S Recommended pumping rates
Abslraction is recommended from barehele 4198, 4202, 4232 and
4234 (4266) uouth of the village, and from 4258/4345/4346 and
4448, north of the village. The three boreholes 4258 etc. sre all
close together and in practice only, one, the most efficient, should
be used.
Pumping rates hnve been calculated south of the village
assuming a Theis dra\:ldowo and pumping rates have been selected so
that pumping water level does not reach breaklllJlay position \IIithin
SOD days. The recommended rates are given in Table 14 from which the
quantity of lIIater available from the boreholes south of village is
360 m'/d . Selecting a pumping rate for the Waterberg aquifer boreholes
4258 etc. snd 4448 is more difficult because the aquifer response does
not fit the Theis model. (1n the basis of ll ~;ting at high pumpLng
rates and extrapolation of the drawdown t a pumping rate of 30 n/h
(720 m'/d) is provisionally recommend from both sites provided water
level monitoriny is carried out. The quantil y of wster ovailatle
from both areas ia thus 1800 m'/d. T
•
10. PULLUTION
l"1ochudi has a certain notoriety as rCf)ards pollution because a
sUlvey Ollce idcntifird Lhe villulJc a:l onc of lhe IIIOI'!;!. ulfl'cted of ... 11
major villslJcs in the country . Sever ... l pol1ulioll sludlCU have lherefure
rightly or wrongly rocussed on r"ochudi. for this reason a fairly full
account of the pollution sHunt ion is given in this section.
10.1 Introduction
Pollution in Mochudi concerns hiyh nitrale and bacteria in the
water sUI-lPly.. Hif)h levels of nitrate in excess of the \mo limit
(45 mg/l) were nol suspected in groundwater in Botswana until
investigation!) b)' the G510 Project discovered NO) in some Serololc
village borcholc!.i durintj sampling in September and December 1975.
follo'lllinlJ this discovery a rapid reconnaissance of the major vi11aye
walers al 11ocllUdi. 1 homage. 1101 clJololc. r-toshupa, Kanye and RamotslJa
(Hullon, lClOIis, l)nd Skinncr, 1976) revealed that high nitrate was
pre'lent In mosl vill<Jges and very high nitrate (exceeding 500 mgll)
was observed in Game borcholes.
High amount!; of nitrates are known to cause methaerniglobinaemia
in infanl s. Thone less than 6 monlhs old are at greatest risk , and
th,' nitrate cannot be removed by boil ing. An international slandard
UIJI 'r limiL of 4~ rntJll NUJ is acceptcd by most countries !Jut ~ome
bcJ leve d hj'lller l.ifllil. lo be safe . ror cxample West Germany and
S\:JJ t7erland ,1110101 9U mq/l NUJ - . In arid countries dependent on 'I:Ic11
wa! er hiyher safe levchJ 0110101 more water to be regarded as potablo so
thl t a highel uppcr limit is reasonable. Botswana currently adopts
an upper lim t of 100 mg/l, and if no elternative supply is available
\1111 ern contH n.hllJ >100 mg/l could be considered.
• b
• • fI IiI
• • I I I I
• i I I I
• • • • • •
.~,
IIlC ~;uul'ce uf hicJh n.iLralc in yroumllllaler i~ eUl"ft:nUy under
jnvc~liyaUoll .in many coull l ries \!Ihere iL is uflen rel<.ilcd lu
intensive farming and application of nitrogen fertilizer. In
Jlot~:Iat;U101 t hir: ~:(JI JI"['C i :l ruled oul muJ t.he mcmt l ikely !>ourcc i~ fr om
11Ulllan and animal excreta. The l11gh nitrale content observed at some
c.:u lUe-posL uoreiloles supports this idea. A recent study (Heaton,
Ta1mn and Vogel, 1983) suggested that some nitrates (up to 100 mg/ l )
do exist naturally in some Kalahari aquifers \IIhich are unaffected by
pollution . There is hovcver little doubt that the high nitrate and
fl'esl bacteria in waters at ~1ochudi. and the other villages , is due
to contamination from pit latrines as sever al studies have shollln .
l U.2 Previous pollution studies
10 . 2 .1 Ilullon, le..,is and Skinner , January 1976
Durlny the original survey by Hutton , l ewis andSkinner in 1975 ,
9 borchol e~ latith high nitrate \!Iere identified in Mochudi. All of these,
s ynificantly lLIere north of the river. T\IIo barehol es south of the river
(1'50 , 2108) \IIere unaffected as the table below sho\lls :
Nitrate (mg/I ) Ni t rate (mo/])
Ilorehole Jan. l?76 May 1976 Uorehole Jan. 1976 rlay 1976
35 199 208 § 1018 51 4 603
38 346 414 1162 100 75
709 284 j63 2108 18 15
792 170 203§ hosp ital dam 503 584
850 8 5 t ap · wa te r 21 -sec . ech o
§ Col ifor m bacteria presen t .
• • • • • • • • • •
the intermitlent prcDcllt:c of fccill bacteria .111 Llle !.>lnndpipc nlld
Innk samples in st'clions of plpc\IIork remole! from a possible conneclion
wilh:l t:wll:nnill;.lcd hurchaIc evidenl 111 I IIJurc 34 doc!.> t.OlJlJycsl
umlarnjnalion from the 5011 thruugh the pipcuork . Il I:; il fact tll ,lt
tile pipe j{l.lllls uf the 110chudi reliculnllon ~lrc uf poor qualily and
fHirly rcqulnr pipe r<lHurc~ il'fl{hny dcpressurisnlion do occu r . It
1:; more j ikcly lhcrcforeUHll Lhe ~Lundpipc cOflLwninalioll 18 frurn this
!iUUreD .
1 U. 4 Summa ry tlnd rccommcnda II un~
The D'luree o f hjyh nilrLltc and chloride 111 parl of Lhe lIuchudl
walel' s uppl y is from Plt lalrines . lhcsc conl:lllliFwrllG enler Lhe
8011 <Ill!! lIlI' aquifer from latrines in an area of high houoing
dCI15ity rlorth of Ihe rlver. fhe potC'nilal for C'ontaminntjOIl from
IGtrlnc:::; 1:.; alva):; prc5cnt but is part Ir.:ular l y hiqh in <.IredS of
thin soil and rock outcrop . The intcrmittent prc!:>ence of focal
baclcrw 1n llOfehole 850 indicates a contamin<lllon of the Clqulfer
t losc to Lhe borehole or direct contaminotion via the boreholc itself.
IIlht'r In~1 tllr.:('~ of f'nnlamination arc U10UfJht to nriqc by cun taC"t vith
~uil waLer tllrouyh leuky p1pe joints foUowlIlY depressu ri !wtion. \utc :
( J ) fhe ~uu rce of pollulion cannol be removed. lnch house or
household requir e!; <l pit 1;ltrille :Hld there 1S little that
cun be dOlle lo rpstrict the IllJlnhers lIor lo modify the
desiYIl to min1111.15e the risk excepl tu avoid fracturing the
rock durlnfJ cOfldrucLioll. 50rne improvemcnt in the locallon
of fulure latrilll'G could be made but lhere is limited scope
in thi s direction.
('1. IlepJacernenl of the polluled S(lurC'~:l by Ill'\:I :lupplics is a
soluLlon . Sufficient 'load qualHy water is avai lable from
lhe aren to Lhe norLh of Lhe villa4c thaL borehole 2764 ond
Y)')U cuuld be Lakcn ouL or scrvicc . Hmi/ever iL i~ rcculllInclldcd
LhaL corlSLrucLion of 0 cenLral sloraqc lank \II1lh chlorine
treatmenl o;hou ld be incorporated into lhe sysLem using Lhe neu
\IIaLer .
0) If a cenlrul storiHJc , d1sLribution and lreatment planl ua::.
construcled it \liQuId alloy waters from the various SQurceu to
be mixed so lhat existing high nitrate waler could be used as
and when required. At present this is not possible because
Uw valeI' goes ~troighl to supply . C('nlrol chlorinatiofl vould
Lll~{) bc !ampJer lo administer lhan Ul(" indlviduaJ chloring
du!;iruJ Lit eacll borehole .
(4) A phased dcvp!opmcnt based on indlvidtlsl borehole connect I un:; la
a ccnlral storage tank is also nlosl Iflg1ca! for future dcv('lopment.
NCIII uupplics could be connecled when discove red ond p("lorcr
• • IiI
• • [j
I qualily exi:Jtinq supplies could be uspd in emc-rgcllcieu. ,\ ~Ile I norlh of lhe river on the high land 1:. recommended bccau~c II('V
~nurccS un' Jjkcly to I'urne from lh<lt I ireclioll and lhe IIl fjil{'r
land providc~ convenient e levati on fur distribuhorl .
r I
• • •
. .
11. ~Ut'V-IAHY I\NI) CIINClUSIUNS
1. Borcholc 4345 una 4440 1n an area of Waterberg rocks 10 km north
• of the village near rlalotoana can together Gupply .... 1500 m'/d of
yood qUcdily waler. • • • 2. 1I0rol1010 42J4, 4198 and 4202 in an area of granite-gneiss 8 km south
east of the village could be developed to supply 360 rn' /d. The
waler from bolh areas is free of high nitrate and is suitable for
all domestic purposes. Together supplies from both areas are
surf IC'lent lo meel the :mLlcipalcd dcm;:lIld of tile village lo 1991
('\.. J UOO rn' ' d ' .
~. All uf the Hlulfprs prcs£'nl in Lhe reglon arp fraclured aquifer';!';o
that cslimalion of the grounduatcr resources in made difficull.
Hcchar(jc lo tile 1.IQUlfers is lcnlnlivcly cntim;;led lu be' 0-.'0 nm / year .
4. The long term I'c!;ponse to purnping in fraclured Aqui fers Callnot be
easily predjctcd and it is therefore recommended that during any
abslraclion the amount pumped and lhe LlQui fer waler levels should
be monilorerl. lid" is especially true of abstraction from t he
Hatcrbery rucks where the aqui fer rcspon"c appears not to follov
lhe normal pollenl.
5 . Groundllloler occurJ'cnce oround r'lochudi is restricled lu a nelvork
of narruw vcrtical to sub-vertical fracture lones in the rocks.
These orc not vell-devcl aped and they sf"parate large blocks of
dry coulllry. The most successful boreholc sites are those vhich
locale I he rnain channel.s or thcir intcr~.ections .
6 . r·luny of the borchules drilled 011 lineamel1ls ond fractures in the
present study \IIcre low-yielding or dry . This may be due to
dri ll inq on the mnrgi nn of the features or moy r eflecl B poor
g r ound\llltcr ci rculatioll through the most prominenL lineaments.
Therc i 1 sOllle evj jcncc tlUlt groundwalcr f irculotiun may actually
prcfcr \("'" U\JV1ULJ!.l lineallcnt and fracture zones .
. ,
• 7. Uun'l!ult.: ~"l1l!y mclhuu~ \l.'ilid, ui!.>crilllilluLc llIlCi.lLiull:. :JIIU
y(>ophyGi~al techniques vhlch illvestiyate lnleral variations
in ruC'k propcrti(1) arc best suiled to identify these aqu ifers.
thp. one si le where .i t tUn') tC!'lLed.
8. It1l' W"lerbertJ area north of the viJlayc offers better prospects
fur dl'vf~lopHlcnl than the granite-gneiss <)t'ca . lhc l<Jrycsl borehole
YIelds were oblained from faulting in the Masama Sandstone of the
Upper Walerbcry. Do lertlc intrusion is frequently related to
:,lruclurol disLtlrlJ<uH:e lhrouylloul lIle ureil cllld loC<.Illy may irnprovc
the perllleab111ly .
9. Struclul'cs in the !'lillstone units of the WatC'rbery rocks <Ippear
less productive allhough this conclusiofl may be influenced by
marginal sHinrJ. but Lhe brittle-fracture response of t.he
9andsLullC units tu faull ing and intrusion offers greater groundwatcr
potentiAl.
10. lhe waLer levels i n Lhe present village wellfield appear Lo be
declining and 1111 a!>sociated reductlOn ill borehol e yie ld is
r'vidr'lll. This is ueli['ved due to exces'; current nbstraction ,
esl imulcd at appro'(imat'!ly 50 mm/year , compared to current , I'ccllary" , esLirnoLcd approximalely at O-lU mm/year. Ihe situCllion
should be monitored.
11. Ihe pollution problem in r10chudi was invesUgated aud should be. •
viewed as a iO l:a l fcalure arisiny from 0 combillolion of C.1rcumslances .
It is COllfined lo only : 1 smal l area. Ihe pollutioll problem can
be avoided a llogelher by locllting water supply boreholea avay from
hou nllltJ 0 1' arcOIn of slock yrnzing.
12. It is rec",",,",ulcd that rutur,' ground.aL,· r exploratioll s hould
concenlraLe initially on the Masama rormation of the Waterberg rockS
norlh .. fld l1urlhwenl of the vlllayr, and aIno lo Lhe east if they all'
idellUnerl in that arcn. Subsequent tu the development of these
~~lJPpII CU lu ,"ll!c l yruurH.Jwulc r \iluult..1 huve Lu cume I1'UIII ~L\'uc.:Lun::s
in lhe Ka1'oo roc ks rurther norlh .
•
I~ '.p q
• • • ~ U I
I I
• 11
• • • JI
• • 11
• • • • • • •
12. mrUIlNCLS
Oa\ilden r1. G. tlnd S tullhs A.II.
llil'r"chCllk w.n. and WilnUIl G.IL
Billon, rarrah, Huskin , Bulncr LlIUJ rhuu.
Brl.'fcton N.H.
(dell H .N. and Haz(' I LP.
fast er 5.5.0. I fnrr J.l. and lewls W.J.
Sj r Al c)(and(' r {; i hh iJllcI
Pm-tnrrn
GrOfll S .
IIIJlcttillA D.G. ltJld ll'il P.
I/ullurt, l.G. I f'win ~J.J. and SI.( j IIlIcr A. Co
.JUI rp!] I) . L. r lid f1:( j h i Illll'y '-1. \4.
1963 The land flcsuurccs of (nntcrn Occhuanaland lnnd Hcsources lHviniun . OOA.
1961 In Synlposium of Alhens, ~oundwater in Arid Zones , Pub 57. l nt. Assoc . Sei . Hydrol. 3. p b07-627.
]9U3 Survival of Pathogenic and indicator organisms in yroundwsler. Grounduater 21 . 4, P 405-11.
1979 Step druwdown pumping tesls for the delermination of aquifer and borehoJe characteristics. Tech. rep. TA 103, Water Research Centre . Ne dmenham U. K •
197) Computer and graphical analysis of variable discharge pumping tests. Civil [ng. Trans. Inst. Eny. Auslr . 5-10.
1978 A detailed evaluation of the pollution hazard to village water-supply boreholes in eastern Botswana . Geological Survey Report GSIO/A.
1975 feasibility study fur vater supplies to f10lepoh le and f.1ochudi villages.
1983 Guide to rlochudi. Phuthadikobo fll rseum Publication.
1983 A short noee on a h} drogeophysica l survey COnt ucted for tile Mochudi u'nahgrc und vater pI eject. Geological Sun ey 11,·". UGH/J}(O}, PI J IS} .
J 976
1966
A report on nitrate contamination of groundwater in Sl me populated areas of Botswana. Geological !itJfvey Hcport. UG-~.o/8/76.
f' ;dacomaynelic corr .. latioll of h<.l9ic inlrusions in the Prccambrian of South Afri r B.
J. Geophy. lie • . 71 2) 54}- 552 in. Kcy R.f1. (1980_
.lUllC':i, ~1. I.
Key, l(.f1.
Kuhut, A.P. , fOli/eraker, J.c., !lodge ~j. S.
Lewis, footer, Read Dnd schcrlenlcib
t1achacha I. r. and Key IL[\.,
i.ldJu'4lell . P .H.
!liller U.B.
IllH hlld I l)f've lupml'l1L PI all
11u ( 101 I I • I ••
ne.1 [LI\. <.Ind Upchurch S.U.
Hulltl'ru J.t'.
Honen D., Kanri , end '1agaritz M.
1966
IYUO
19U;
1981
in prep
1979
19')2
198;
197H
1901
1980
1970
1983
ISO
Ihe l;co ltltJY of Ihl: f1ochw.li <Ind (lad Iliver area. (an explull;'llioll of qu;.trlcr dcyree sheets 2426A, 24260. Geological Survey Ucport IHJ/37/66.
Ihe Geuchrolluloyy of Uotsvana. lrnns. gcul. Soc . Afr . BD. p 31-42
Pumping effects of ~el19 in fraclured granitic lerrain. Ground\llaler 21, ~ p 564-573 .
The need for an integrated approach to water supply and san~talion in develop~ng countries The Science of the lotal Environment 21 . p 5.5 - 59 .
Ihe Halerbery 5upergroup in BotswarlH. Gl'uloglcal Survey Oulletin 23.
Geophysical mapping of vatcrfilled fracture lones in rocks. lIlt. Assoc . of Engine('ri l1 Y Gcol()YlstG . .!.! p L)U-26.J.
The \:Iout.ly pl;mts of the Ucchu8nalund Prolet:lurale Jour. of ~j.Arr. Bolany lB. pi-lOO.
• Depurtment of 10llln and Hctjional Plalllllng. Gaborone.
, , . I stimnlllly evapolransp~ral~ulI I rom polential cvap{ ral ion: practicality of an Iconoclastic 'lpproach. Jour. Ily( rolug)' 3H
p 1-32.
lperationa1 estimates of arci:il cvnpol ranspiralioll dnd lheJ.r ~ 1 yni F icullce lo lhl' ::;c iCIlt:e and ~ rnclice of hydroloqy. Jour. I'ydrology 66 pl-76.
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InFluence of flego1ith properties n igration of septic tank eFrllJcnt. (round\llatcr 18, 2, P llH-12~.
Ihe movement of hadcria and \ iruses lhruuyh ponus rncdl(:1. iround\llaler B. 37-4l .
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5 )urces of ni ttoles in Groundwaler of the Conslal PlAin of brae!. IlaL. neR. Ill. p1499-l50.L
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uf vull'1 ~uppli('~; in till' 1I1dJOf
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or H<'tLl'f Arf'Jir'; .
Geoloqy ,mu ecunOllllC ['{"iOllrn'" of lhe Bakqill LI Ili'sC'nc . Hp6, l to JC I Co . Lld. GeulOlJjCill <iune} Ileport CH2/2/L .
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Gpulogi C<J I 'iurvC'y Hepo! I P1H12 /56 .
